Characterization of Heat Transport Properties of Polymers for Nanoscale Thermal Processing

摘要低成本、高通量的纳米制造技术是保证现代工程各个领域持续进步的关键技术，尤其是信息处理、存储和通信技术。许多新兴的纳米制造技术需要对薄的（100纳米）聚合物薄膜进行精确的热加工。例如，纳米压印技术使用包含纳米级浮雕图案的刚性模板，机械地使加热到玻璃化转变温度以上的聚合物层变形。所得到的图案化聚合物可作为后续纳米制造工艺的掩蔽层。局部加热也可以用来选择性地交联嵌入纳米颗粒的聚合物，以产生微纳米尺度的特征。控制加热起着重要的作用，因为在聚合物薄膜中发生的物理或化学过程的动力学是温度的敏感函数。基于物理的聚合物加工设计和优化需要对热输运有基本的了解。在纳米尺度上对基础研究的需求尤其迫切，因为纳米约束和其他表面/界面效应预计会强烈影响聚合物的行为。本研究开发了微型实验平台，用于研究纳米级聚合物薄膜在发生物理或化学转变（如玻璃化转变和聚合）时的热传递。在局部瞬态加热过程中，聚合物薄膜的热传递特性和物理化学转变的空间范围将被确定为温度和加热速率的函数。提议的研究在本质上是高度跨学科的，并解决了大分子系统中传热的基本方面。该研究的实验数据将为纳米级聚合物动力学提供有用的见解，这是具有重大科学意义的。通过提出的研究获得的基本理解也将使系统地探索新的热处理方案以及优化现有的聚合物纳米级热处理方法成为可能。这项研究也为培养研究生和高级本科生提供了一个令人兴奋的机会，并帮助他们获得跨学科的技能。学生将有一个非常有益的经验，即从事具有重大实际意义和公众认可的项目，他们的贡献可能会产生直接影响。建议研究的这些方面将特别有助于激励本科生追求工程/科学事业。该合同由化学和运输系统分部的热传输和热处理项目提供支持。

AbstractLow-cost high-throughput nano-manufacturing techniques are critical in ensuring continued progress in diverse areas of modern engineering, especially the information processing, storage, and communication technologies. Many emerging nano-manufacturing techniques require precise thermal processing of thin ( 100 nm) polymer films. The nano-imprint technique, for example, mechanically deforms polymer layers heated above glass transition temperature using a rigid template that contains nano-scale relief patterns. The resulting patterned polymer serves as a masking layer for subsequent nano-fabrication processes. Localized heating can also be used to selectively cross-link polymers embedded with nano-particles to produce micro- and nano-scale features. Controlled heating plays an important role because kinetics of physical or chemical processes occurring in polymer films is a sensitive function of temperature.Physics-based design and optimization of polymer processing requires fundamental understanding of thermal transport. The need for fundamental studies is particularly acute at nanoscales because nano-confinement and other surface/interface effects are expected to strongly influence the behavior of polymers. The proposed research develops micro-fabricated experimental platforms to investigate thermal transport in nanoscale polymer films undergoing physical or chemical transformation, such as glass transition and polymerization. The thermal transport properties of polymer films and spatial extent of physico-chemical transformation during localized transient heating will be determined as a function of temperature and heating rate.The proposed research is highly interdisciplinary in nature and addresses fundamental aspects of heat transfer in macromolecular systems. Experimental data from the proposed research will provide useful insight into nanoscale polymer dynamics that is of great scientific interest. Fundamental understanding gained through the proposed investigation will also enable systematic exploration of novel thermal processing schemes as well as optimization of existing nanoscale thermal processing methods for polymers.The research also offers an exciting opportunity to train graduate and advanced undergraduate students and help them acquire interdisciplinary skill sets. Students will have a very rewarding experience of working on projects of great practical relevance and public recognition where their contribution can potentially make direct impact. These aspects of the proposed research will be particularly helpful in motivating undergraduate students to pursue engineering/scientific career.This award is being supported by the Thermal Transport and Thermal Processing Program of the Chemical and Transport Systems Division.